/ˈlaNGərˌhanz/ /ˈläNGərˌhäns/ Plural, islets of Langerhans 1. The regions of the pancreas that contain its endocrine (i.e., hormone-producing) cells. Discovered in 1869 by German pathological anatomist Paul Langerhans at the age of 22, the islets of Langerhans constitute approximately 1 to 2% of the mass of the pancreas. (wikipedia.org) 2. Regions in the pancreas that contain its endocrine cells (wiktionary.org). 3. Irregular clusters of endocrine cells scattered throughout the tissue of the pancreas that secrete insulin and glucagon. (thefreedictionary.com) Syn: Islands of Langerhans, isles of...